1. Field of the Invention
The present invention relates to a method of identifying a serotype of Klebsiella pneumoniae, in particular to a method using specific polymerase chain reaction (PCR) primer sets designed according to a fragment of a capsular polysaccharide synthesis (cps) region to identify a K57 or a NTUH-N1 serotype.
2. Background of the Invention
Klebsiella pneumoniae belongs to the family of Enterobacteriaceae; which is a Gram-negative, facultative anaerobic, rod shaped bacterium with polysaccharide capsules. It's an opportunistic infectious pathogen. Strains of Klebsiella pneumoniae exist in the respiratory or digestive tract of healthy people. Infection occurs most commonly in people with low immunity that usually causes serious infection, and may result in pneumonia, septicemia, urinary tract infections, or wound infections and the like.
Pyogenic liver abscess caused by Klebsiella pneumoniae, which was always combined with septicemia, was found with unique clinical characteristics over the past two decades. This is a global emerging disease, particularly common in Taiwan. Different from the traditional disease caused by Klebsiella pneumoniae, people acquired this disease led an active daily life prior to hospitalization. Most patients do not have intra-abdominal infections or biliary tract diseases but may have peritonitis or septic shock, or may further be combined with bacteremia, septic endophthalmitis, meningitis, and so on.
The known virulence factors of Klebsiella pneumoniae include capsular polysaccharides, lipopolysaccharide, adhesions, membrane and extracellular protein. Among them, capsular polysaccharides are the major virulence factor and the base for serotype classification. There are at least 77 serotypes for Klebsiella pneumoniae according to serum epidemiology. The virulence of each strain varied with serotype. For example, serotype K1 or K2 has higher severity of infection (more virulent) than others, which cause pyogenic liver abscess easily, followed by combination with meningitis and endophthalmitis. The identification of serotypes was carried out by immune response using the immune sera (antibodies) to react with the extracted capsules of Klebsiella pneumoniae from the patients to determine the precipitation line with the reference strains of all serotypes. However, drawbacks of this method include low specificity, low sensitivity, and high expenses of serum.
Pyogenic liver abscess induced by infection of Klebsiella pneumoniae is susceptible to first generation antibiotics cephalosporin and gentamicin. However, mortality as high as 10-20% for primary liver abscess and as high as 30-40% among those with meningitis has been reported with effective doses of antibiotics. Due to the serious and invasive Klebsiella pneumoniae disease in epidemiology, it is important to develop a Klebsiella pneumoniae serotype detection method to facilitate the early diagnosis and rapid treatment in order to lower the mortality and provide insight to the prevention and treatment of diseases associated with Klebsiella pneumoniae. 